JPS6036724A - Intake apparatus for internal combustion engine - Google Patents

Abstract

PURPOSE:To promote vaporization and mixing of fuel at the time of starting an engine by use of high-speed flow of intake air supplied from a subsidiary intake passage, by employing such an arrangement that a second throttle valve is closed forcibly at the time of cranking. CONSTITUTION:At the time of low-load operation of an engine, the negative intake pressure acted to a vacuum actuator 11 is increased, so that a second throttle valve 8 is closed. In this state, most of the air-fuel mixture is introduced into a combustion chamber 10 from a subsidiary intake passage 9 having a small sectional area. At the time of high-load operation of the engine, on the other hand, the second throttle valve 8 is opened since the negative intake pressure is low, so that the air-fuel mixture is introduced into the combustion chamber 10 mostly from a main intake passage 4 having a large sectional area. At the time of cranking the engine, a starter switch 16 is turned ON and current from a power source 15 is passed through an electromagnetic coil via a relay 17, so that a movable sleeve unitary with a diaphragm is pulled upward and the second throttle valve 8 is forcibly kept at its closed position regardless of the vacuum force.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to an intake system for an internal combustion engine such as an automobile, and in particular, in addition to a main intake passage that supplies intake air to the engine, a sub-intake passage for promoting atomization and vaporization of fuel is provided. Concerning things with passages.

(Background and Prior Art) Generally, during low-load operation of an internal combustion engine, particularly in a low-speed, low-load range, the filling efficiency of intake air taken into the combustion chamber is low, so the flame propagation velocity is low and combustion is unstable. For this reason, the thermal efficiency of the engine is low, and due to incomplete combustion, HC in the exhaust gas
, CO increases, and other problems.

Therefore, in recent years, we have started to create moderate turbulence in the outside intake air in combustion chambers, etc.
As a result, methods have been adopted to increase the flame propagation speed.

Conventionally, there is an intake device that adopts the above method, as shown in FIG.
(see publication).

First, the gathering part of the intake manifold 1 is placed as close to the intake valve 5 as possible in the main intake passage 4, which consists of each branch pipe 2 of the intake manifold 1 and each intake boat 3 of the engine to which the branch pipe 2 is connected. 6 Carburetor throttle valve installed upstream 7
Separately, a second throttle valve 8 is provided which closes in the low engine load range.

Then, a sub intake passage 9 is provided, the upstream end of which branches off from the main intake passage 4 upstream of the second throttle valve 8, and the downstream end of which merges back into the main intake passage 4 near the intake valve 5. .

The downstream opening 9A of the sub-intake passage 9 is formed on the bottom wall of the main intake passage 4 (intake boat) so that the jetted air-fuel mixture flows approximately horizontally into the combustion chamber 10 when the intake valve 5 is opened. It is opened at 4A.

In the figure, 11 is a negative pressure actuator for opening and closing the second throttle valve 8, and its negative pressure chamber 11A is communicated with the main intake passage 4 downstream of the carburetor throttle valve 7 via a negative pressure passage 12. In response to the engine suction negative pressure, the diaphragm IIB is driven upward in the figure in the engine low load region where the negative pressure increases, and the second throttle valve 8 is activated.
It's about to close and operate.

Therefore, in a low engine load range when the second throttle valve 8 is closed, most of the air-fuel mixture is sucked into the combustion chamber 10 through the sub-intake passage 9 with a small cross-sectional area; The downstream opening 9A of the intake passage 9 is opened in the bottom wall 4A of the intake boat 3 so that the ejected air-fuel mixture flows approximately horizontally into the combustion chamber 10. Swirling flow (
swirl) is generated.

This promotes the atomization and vaporization of the fuel in the air-fuel mixture, improves the combustion efficiency of the air-fuel mixture, increases the combustion rate, and improves the combustion state in the relevant operating range.

On the other hand, in the high load region of the engine when the second throttle valve 8 is opened, most of the air-fuel mixture is transferred to the intake boat 3 with low passage resistance.
Since the fuel flows into the combustion chamber 10 through the fuel, high charging efficiency can be obtained.

However, in such conventional intake systems, the second throttle valve 8 described above is simply opened and closed by a negative pressure actuator 11 that responds to the engine's suction negative pressure. When the engine is cranking, where the pressure is high, the second throttle valve 8 is kept open, and when the second throttle valve 8 is closed, the intake air flow speeds up and the turbulence promotes fuel vaporization and mixing. There was a problem that no effect could be obtained and the startability (especially low temperature startability) could not be improved.

(Purpose of the Invention) This invention was made by focusing on such conventional problems, and it is possible to avoid the vaporization of fuel by the gas flow as described above, not only in the low load range of the engine but also during cranking. It is an object of the present invention to provide an intake device that can obtain a mixing promotion effect.

(Structure and operation of the invention) In order to achieve the above object, the present invention first includes a main intake passage which communicates with the engine combustion chamber via an intake valve, and which is located downstream of the carburetor throttle valve. A second throttle valve is provided, and a sub-intake passage is provided so as to branch from the main intake passage upstream of the second throttle valve and rejoin the main intake passage near the intake valve.

The second throttle valve is closed in a low load range of the engine by a negative pressure actuator that responds to the engine's suction negative pressure, and is attached to the negative pressure actuator and is closed during cranking of the engine. The closing means is adapted to be closed even when the engine is cranking, by the closing means responsive to a signal from the means for detecting the engine.

In other words, when the engine is cranking, the second throttle valve is held open by the negative pressure actuator because the engine's suction negative pressure tends to develop.

In the present invention, this valve is forcibly closed by the closing means described in -F.

According to this, most of the air-fuel mixture flows into the combustion chamber through the auxiliary intake passage not only in the low load range of the engine but also during P-cranking, and the effect of promoting fuel vaporization and mixing due to gas flow is reduced. As a result, startability is greatly improved.

(Example) Next, embodiments of the present invention will be described based on the drawings.

2 (4), (0) indicate the first embodiment of the present invention.

In the figure, 1 is an intake manifold, 4 is a main intake passage leading from a branch pipe 2 of the intake manifold 1 and an intake boat 3 of the engine;
8 is a second throttle valve provided in the main intake passage 4 separately from the carburetor valve 7; 9 is a sub-intake passage that bypasses the second throttle valve 8; This is a negative pressure actuator for opening and closing the throttle valve 8 of No. 2.

Up to this point, the configuration is the same as that shown in FIG. 1, but the feature of this embodiment is that the above-mentioned negative pressure actuator 11 is turned ON only during cranking as a means for closing the second throttle valve 8 when the engine is cranking. An electromagnetic coil 13 is attached, and the negative pressure actuator 11 can be operated by magnetic force regardless of negative pressure.

In other words, the electromagnetic coil 13 is connected to the negative pressure actuator 11.
In the negative pressure chamber 11A, the movable cylinder 14 made of a magnetic material integrated with the diaphragm 1113 is moved upward (ν1) in the figure against the return spring IICK when it is turned ON (energized).
In addition, the power supply 15 is provided so as to be able to attract air in the direction in which the second throttle valve 8 is closed.
The circuit is connected via a relay 17 that turns FF.

Further, in this embodiment, the downstream opening 9A of the sub-intake passage 9 described above allows the ejected intake to directly flow into the spark plug 18.
The opening is oriented in such a way that it does not hit the object.

The rest of the structure is the same as in FIG. 1, so the same members as in FIG. 1 are given the same reference numerals and detailed explanations will be omitted.

Because of this configuration, when the engine is operating other than during cranking, the starter switch 16 is turned OFF, so the electromagnetic coil 13 is not energized, and the negative pressure actuator 11 is not energized by the engine's suction negative pressure. In response, the second throttle valve 8 is controlled to open and close in the same manner as before.

A negative pressure actuator 11 is installed in the low load range of the engine 1.
The second throttle valve 8
is closed, and most of the air-fuel mixture flows into the combustion chamber 10 through the sub-intake passage 9, which has a small cross-sectional area, so as mentioned above, the gas flow level is increased and combustion is improved. on the other hand,
In the high load range, suction negative pressure develops, so the second throttle valve 8
opens.

Since the air-fuel mixture mainly flows in through the main intake passage 4 having a large cross-sectional area, the output is ensured.

Next, when cranking the engine, start switch 16
is turned on and current from the power supply 15 flows through the electromagnetic coil 13 via the relay 17, so the movable cylinder 14 integrated with the diaphragm IIB is pulled upward in the figure, and the second throttle valve 8 is brought into negative pressure. The valve is forcibly kept closed regardless.

As a result, even during cranking, when the second throttle valve 8 is closed, the effect of promoting vaporization and mixing of fuel due to the flow of soot can be obtained, and startability is greatly improved.

In addition, since starting performance has been improved, the choke set during cranking can be leaner, reducing fuel consumption during starting and warming up.
There is also the advantage that emissions etc. are greatly improved.

Furthermore, in this embodiment, the downstream opening 9A of the auxiliary intake passage 9 is oriented as described above to prevent the fuel from directly hitting the spark plug 18, so that smoldering of the spark plug 18 will not occur. There are also some advantages.

3 and 4 show second and third embodiments of the present invention.

FIG. 3 shows a negative pressure chamber 11 of a negative pressure actuator 11 as a means for closing the second throttle valve 8 during cranking of the engine.
A solenoid valve 20 is provided in the negative pressure passage 12 connecting A and the main intake passage 4 downstream of the carburetor throttle valve 7, which is a negative pressure source.
' is a rotary switch 19 as a means for detecting the cranking time (this is lower than the idle speed, e.g. 500 rpm).
Turns ON in response to ~60Orpm or higher) -
I turned it off. Generally, when an engine is stopped, it is stopped after passing through the idle state, but while the strong negative pressure at this idle state remains in the negative pressure chamber 11A, the rotary switch 1
9 becomes OIi'F. Therefore, the valve body 2O of the solenoid valve 20
A protrudes from the return spring 20B to block the negative pressure actuator 11's i! 1.
The high negative pressure is locked in the +E chamber 11A, thereby keeping the second throttle valve 8 closed.

According to Kone, when the engine is next started, cranking is started with the second throttle valve 8 closed, so that good startability can be obtained as in the first practical example.

FIG. 4 shows an example in which a throttle switch 21 is used instead of the rotary switch 19 in FIG. 3.

According to Kone, even when the carburetor throttle valve 7 is fully closed during a cold start (larger than when it is warm), its contact point 2]A is OF.
The shape of the cam 21B is set to be 'Ii', which has the advantage that it can also be used as the throttle switch 21 for force, movement, and IJW'yt.

(Effects of the Invention) As explained above, according to the present invention, the second throttle valve is forcibly closed during cranking by the predetermined closing button means that responds to the signal from the means for detecting cranking. Therefore, even at the time of starting, the high-speed intake air flow from the sub-intake passage allows the vaporization and mixing of the fuel to proceed rapidly, resulting in a significant improvement in starting performance (starting time, limit temperature, etc.).

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional example. Figure 2 is a schematic diagram of the first embodiment of the present invention (M factor); Figure (B) is a plane i+1 view of the main part thereof, and Figure (C) is a cross-sectional view of the main part. Fig. 4 is a schematic configuration diagram of each of the second and third embodiments of the present invention. 10... Combustion chamber, 5... Intake valve, 4... Main intake passage, 7... Vaporization Throttle valve, 8...Second throttle valve, 9
...Sub-intake passage, 16...Starter switch, 19
...Rotation switch, 21...Throttle switch,
11... Negative pressure actuator, 13... Solenoid coil, 20... Solenoid valve. Patent Applicant: Nissan Motor Co., Ltd. Representative Patent Attorney Masa Goto Iwa Figure 1

Claims (1)

[Claims] 1. An intake throttle valve in the main intake passage and a second intake throttle valve located downstream of the intake throttle valve.
A throttle valve is provided, and an auxiliary intake passage with a small cross-sectional area is provided that branches from the main intake passage upstream of the second throttle valve and joins the main intake passage again near the intake valve. In an internal combustion engine equipped with a drive means that closes a valve in a low engine load range and opens it in a high engine load range, there is provided a means for detecting when the FA engine is cranking, and a signal from the detecting means to control the second throttle valve during cranking. An intake device for an internal combustion engine, characterized in that it is provided with means for forcibly closing a valve. 2. The means for forcibly closing the second throttle valve 9 is installed in a negative pressure actuator that drives the second throttle valve in response to the engine suction negative pressure, and is energized when the engine is started to close the second throttle valve. ML magnetic cocoil for driving a throttle valve Claim 1
An intake system for an internal combustion engine as described in . 3. What is the means for forcibly closing the second throttle valve? A negative pressure actuator is installed in a negative pressure passage of a negative pressure actuator that drives a second throttle valve in response to engine suction negative pressure, and when the engine is stopped, the negative pressure passage is closed and the negative pressure in the negative pressure chamber of the negative pressure actuator is reduced. An intake system for an internal combustion engine according to claim 1, which is a solenoid valve that locks the intake system.